The present invention relates to a device for elevational displacement of the eyepiece of a microscope having a removable tube.
Most of the known conventional microscopes have a removable tube having a length of about 16 cm. The objectives used are corrected for this tube length, which is inter alia also a factor in the stated magnification of the microscope. And in any new designs, this length must at all times be recognized if importance is placed on compatibility with existing accessories.
Larger research microscopes, to be sure, frequently have a greater tube length, a different length of for instance 20-25 cm, obtained by means of an auxiliary lens system. But there is an inherent accompanying increase, by a factor of approximately 1.25.times. to 1.5.times., in image scale of the objectives used, resulting in an undesired reduction in the size of the visual field.
In ordinary conventional microscopes, the removable tube, which is frequently also developed as a binocular tube, is arranged in such manner that the viewer looks into the eyepeices inserted therein at a viewing-aspect elevation of between 30.degree. and 45.degree. to the horizontal, since in the normal working position the view is, after all, in a seated position, in front of the microscope, which stands on a table. Oblique observation within this angular range is therefore adapted to the ordinary height of the body of the observer.
In recent years, increasing specialization of laboratory activities towards fewer fields of work has had the result that certain groups of persons work in front of the microscope in a sitting position for the greater part of the day. With longer continuous work on the microscope, the shortcomings of traditional mechanical microscope constructions have become increasingly more evident. Many users assume an unnatural, uncomfortable position and, in the further circumstance of monotony of the work, cramps, headaches, and pains in the neck, back and arms are the result. Because of the mechanical tube length of 16 cm, the microscope itself does not have the dimensions which are best adapted to the dimensions of the human body. The microscopes are too short, i.e., the distance between eyepiece and tabletop does not agree with the distance which should be present between the eye and the arm which is resting on the tabletop. The operating parts of the microscope stand are arranged too close to the body, and the viewer is always too tall as compared with the microscope; he must either incline his head downward if his arms are to rest comfortably on the tabletop, or else he must sit too low in order to be able to direct his eye properly onto the eyepiece, and in the latter case the tabletop is so high that he is forced to sit with his shoulders and arms cramped. Short persons therefore have the least difficulties, while the difficulties are greater for persons of average and greater-than-average height.
By suitably shaping the furniture, and in particular the table, it has been attempted to improve the working position of the microscope user. However, it has not been possible thereby to significantly affect the sitting position.
The anatomical shape of the human body makes it desirable to arrange the eyepieces of a microscope at such a distance away from the remaining part as to correspond to the distance between the eyes and the hands of the viewer when the latter is seated in an erect working position in front of the microscope. Furthermore, the eyepieces should be adjustable in height so that they can always be adapted to the position of the body of the viewer, which position changes during the course of prolonged working hours.
U.S. Pat. No. 2,439,526 discloses a microscope which contains an eyepiece with variable observation angle. Although this construction provides a rather large range of adjustable observation angles, it does not permit any significant possibility of vertical adjustment due to its short swing lever, and it has the above-described disadvantage of the anatomically unfavorable short structure.
German patent application No. 2,654,778, describes a stereoscopic tube for an operation microscope with variable observation angle, the instrument being designed specifically for observation close to the object; but this instrument also has the above-noted disadvantage. The microscope tube is kept extremely short by multiple bending of the ray path in order to assist the viewer, in assumption of a relaxed working position; however, in the normal case, the viewer is working not on the microscope, but on the patient.